My elliptical sporadically increases resistance. I can go through 1-8 w/no problem but when I go back to a 4 or 5 resistance level it is harder than a 10 resistance. So then I have to bring it down to 1 and it runs smooth all the way depending on the mood of the machine. Sometimes the resistance will be stuck in a 10+ mode for a while and other times just by going down to a 1 and then back up to a 5 it works itself out. ???? Any suggestions? Thanks so much.